Modern original equipment manufacturers (OEMs) have two primary options for choosing plastics for their projects — thermoplastic elastomers (TPEs) and liquid silicone rubber (LSR). While the latter uses the term rubber, it’s a thermoset that remains part of the elastomer family.
What Is an Elastomer
The word “elastomer” is a combination of the words elastic and polymer. It is a material with both viscosity and elasticity, known as viscoelasticity, that allows the material to return to its original shape and size after significant stretching or compression. Many elastomers are synthetic materials based on Polysiloxane and can outperform organic elastomers, like natural latex, in some applications.
In chemical terms, a thermoset elastomer like LSR boasts covalent bonds in which atoms share electrons. The makeup differs from TPEs, which typically have weaker hydrogen or dipole bonds.
Why Is LSR an Elastomer?
In addition to their extensive stretchability, elastomers share other distinctive physical and mechanical properties that help classify them.
Temperature Behavior and Electrical Insulation
The heat resistance of elastomers varies depending on the underlying elements involved, but all of them exhibit tolerance to higher temperatures. Likewise, different compounds can handle assorted cold temperatures before reaching their brittle points. Another common property among elastomers is their natural electrical insulative properties and ability to resist electricity.
LSR can withstand consistent exposure to temperatures between -40°C to 200°C (-40°F – 392°F). It’s also a dielectric material, making it an excellent electrical insulator. These factors make LSR a preferred choice for extreme-temperature applications such as gas grills, water heaters, and automotive and recreational vehicles. It’s also a practical choice for those where conductivity would present an issue.
Some elastomers are also widely known for their ability to resist environmental conditions and abrasion. In addition to withstanding extreme temperatures, these materials can also withstand exposure to elements like water and UV rays without corroding. Additionally, their chemically inert nature prevents negative reactions when introduced to many alkalis, acids, and cleaners. Many elastomers also readily resist abrasion, mold, mildew, and fungus.
LSR meets these criteria, positioning it as a good candidate for applications with longer service-life requirements.
While low-temperature flexibility varies among elastomers, it’s a property they share. That characteristic allows them to retain their elasticity and reduces the potential of cracking in low-temp applications.
LSR retains its flexibility and excellent sealing performance even in temperatures as low as -60ºC. That makes liquid silicone rubbers a reliable choice for performance in the petrochemical and refrigeration industries.
Elastomers generally range between 20 and 80 Shore A. Different hardness levels are reachable through chemical engineering, however, most applications are typically between w0 and 80 Shore A.
LSR hardness can fall between 5 and 90 Shore A, aligning it with other elastomers. By altering the polymer’s cross-linking ratio, LSR-capable compounders can customize the hardness to meet an application’s demands.
Contact SIMTEC for OEM LSR Component Solutions
SIMTEC has over 20 years of knowledge and experience in LSR injection molding to provide our customers with value-added, custom solutions. We’ve built a reputation for providing proven results backed by a passion for quality and customer service.